Salzmann Nodular Degeneration (SND) is a non-inflammatory condition of the cornea characterized by elevated, bluish-white or grayish nodules on the eye’s front surface. This acquired condition typically progresses slowly over time. Whether these growths require surgical removal depends entirely on the patient’s symptoms and the nodules’ impact on vision.
What Are Salzmann Nodules and How Are They Diagnosed?
Salzmann nodules are plaques of hyaline material—disorganized deposits of collagen forming an outgrowth in the anterior corneal stroma, just beneath the cornea’s outermost layer. They often develop following chronic irritation, inflammation, or previous ocular trauma. Risk factors include chronic dry eye, contact lens use, and certain inflammatory conditions.
Symptoms include foreign body sensation, chronic irritation, and fluctuating vision. If the nodules expand toward the center of the cornea, they cause blurred or distorted vision. Diagnosis is achieved through a slit lamp examination, where a specialist observes the characteristic elevated, creamy-white lesions.
Ancillary imaging tests, such as corneal topography and anterior segment optical coherence tomography (AS-OCT), are used to map the cornea’s curvature and thickness. These tools help determine the extent of the nodules’ elevation and whether they are inducing irregular curvature, or astigmatism.
When Is Surgical Removal Necessary?
Surgical removal is reserved for significantly symptomatic patients, as mild cases are often asymptomatic and observed. The decision to proceed focuses on two primary criteria: significant visual impairment and severe, unresolving discomfort. If the nodules are not causing problems, observation is the preferred management strategy.
The most common indication for surgical intervention is decreased visual acuity that cannot be corrected with conventional eyeglasses or contact lenses. This decline is often due to the nodules causing irregular astigmatism or encroaching on the central visual axis. The irregular surface scatters light and distorts the eye’s focusing ability.
A second reason for removal is chronic ocular discomfort, such as persistent foreign body sensation, dryness, or recurrent epithelial erosions over the nodules. If these symptoms are severe and do not respond to conservative medical management, surgery may be recommended. Discomfort or contact lens intolerance can be the sole reason for intervention.
If a patient requires cataract surgery, centrally located nodules may need to be removed beforehand. This is necessary because the irregular corneal surface interferes with the accurate measurement of the intraocular lens required for the procedure. Removing the nodules allows the cornea to stabilize, ensuring more precise calculations for optimal visual outcomes.
Treatment Options for Salzmann Nodules
Management begins with conservative, non-invasive treatments, especially for mild symptoms or peripherally located lesions. This initial approach focuses on improving the health of the ocular surface and managing underlying inflammatory conditions. Treatments often include preservative-free lubricating eye drops, warm compresses, and topical anti-inflammatory medications like steroids or cyclosporine to alleviate discomfort.
If conservative treatments fail or if the nodules cause significant visual problems, surgical management is necessary. The most common procedure is a mechanical superficial keratectomy, which involves manually scraping or peeling the nodule off the corneal surface. The nodule is situated on a natural plane, allowing for easy removal.
Following mechanical removal, the underlying corneal surface may still be irregular. A second technique, Phototherapeutic Keratectomy (PTK), may then be used. PTK utilizes an excimer laser to precisely smooth the corneal surface, correcting residual irregularity and improving the visual result. This combined approach has a high success rate in reducing astigmatism and improving vision.
To reduce the risk of recurrence, an anti-scarring agent called mitomycin-C is sometimes applied to the corneal surface immediately after surgery. In rare cases involving deeper scarring, a corneal transplant may be required.